Wear behavior of a crankshaft journal bearing manufactured by powder spraying

A new crankshaft bearing material that can be an alternative to the traditional material has been improved and its wear behavior studied experimentally. Crankshaft main bearings are subjected to various stresses. A new material supposed to be adapted these operating conditions was designed composing of Pb–Sn–Cu–ZrO₂ and manufactured by HVOF spraying technique. Wear behavior of the bearing was tested with the simulation of real operating conditions. An original bearing was used for comparison. After a trial of 500 h, the weight losses were measured. SEM micrographs of both original and new bearings were examined. The effect of microhardness was discussed. The new composition was seen as promising as a bearing material for automotive engines.     

Seismic microzonation of the historic peninsula of İstanbul

In this study, the geological and geotechnical conditions of old Istanbul (Fatih and Eminönü provinces) were investigated in detail and a seismic microzonation study was undertaken for this historical peninsula, which is the site of many ancient structures. Dynamic site response, liquefaction potential and slope stability analyses were carried out, based on field and laboratory tests and earthquake time histories computed with respect to probabilities of exceedance of 10 and 40% in 50 years. The output data obtained from the analyses were evaluated by GIS techniques, and ground shaking, liquefaction susceptibility and landslide hazard maps were prepared.     

Relationship among fecal coliforms and <Emphasis Type="Italic"> Escherichia coli </Emphasis>in various foods

For much of the twentieth century, coliform bacteria and especially Escherichia coli have been used as indicators of possible post-processing contamination and the presence of E. coli as an indicator of fecal contamination in foods. In this study, 500 foods in 10 different groups, mainly dairy products, delicatessen products, salads, spices, cream cakes and fresh fruit and vegetable samples, were analyzed for the natural contamination of fecal coliforms and E. coli by the standard most probable number (MPN) method. The difference between weighted means of fecal coliforms and E. coli counts were only 0.246 log₁₀ MPN/g-ml (MPN/gram for solid samples, and MPN/milliliter for liquids). Enumeration results were also evaluated by Pearson's correlation coefficient ( r), Cronbach's alpha (f) and determination coefficient ( r ²) analysis. According to results, although 33 samples contained only non- E. coli fecal coliforms, the results of reliability analyses indicated that fecal coliform counts and E. coli counts may be used interchangeably ( P <0.0001). It can be said that fecal coliform or, preferably E. coli analysis is sufficient for rapid routine determination of fecal contamination, at least for those food groups analyzed in this research.     

Organic Carbon and Trace Metal Distribution in the Gökçesu Shale: Eocene Basin,Bolu-Turkey

Abstract

Samples collected from the bituminous shales in the Eocene Tokmaklar formation are the material of this study. Distribution of organic material and trace metals in the shale samples and their concentration levels and correlations were evaluated. Organic carbon content of the bituminous shales is between 0.59 and 15.89% (averaging as 4.86%). The type of organic material is 100% amorphous material (kerogen type is Type I and Type II) and it has a potential to produce oil. Trace metal enrichment levels were determined on the basis of average shale concentration in the earth crust. These levels are divided into two groups. Mo (1.98–2.64), Cu (1.27), As (1.59–8.83), and Sr (2.58–2.75) in bituminous rocks show enrichment character while Pb, Zn, Ba, and Co metals do not display any enrichment. Moreover, comparison with the average values of these metals in seawater and living organisms yield enrichment coefficients of 86.17–386.000 (with respect to seawater) and 4.59–1,723.5 (with respect to living organisms).     

Production of nano zinc borate (4ZnO·B2O3·H2O) and its effect on PVC

In this study, nano sized zinc borate powder with a formula of 4ZnO·B₂O₃·H₂O was synthesized using 2ZnO·3B₂O₃·3.0–3.5H₂O as a starting chemical which was produced using a wet chemical method. After dissolving 2ZnO·3B₂O₃·3.0–3.5H₂O in an ammonia solution, the clear solution was boiled until a white powder formed. The resultant powder was characterized with XRD, FTIR, TGA and TEM. XRD, FTIR and TGA results proved that the powder was belonged to the 4ZnO·B₂O₃·H₂O. Nano composites of 4ZnO·B₂O₃·H₂O–polyvinylchloride (PVC) were produced by injection moulding by adding 1 and 5 wt% zinc borate powders into PVC to enhance its flame retardancy. Limiting oxygen index (LOI) of virgin PVC increased from 41% to 47% and 54% for the 1 and 5 wt% zinc borate added PVC, respectively. Nano zinc borate addition into the PVC does not have considerable negative effect on the mechanical properties of zinc borate–PVC composites even at high amounts of 5 wt%.     

Synthesis and characterization of polyphenols derived from 4-fluorobenzaldeyde: The effect of electron-donating group on some physical properties

In this study, we proposed to investigate how the effect of electron-donating methyl ( CH₃) group at p-position of amin ( NH₂) group in aminophenol (AP) compound affected thermal stability, optical, electrochemical properties, and conductivity measurement. For this reason, we choice 2-AP and 2-amino-4-methylphenol compounds and synthesized phenolic monomers by condensation reactions 4-fluorobenzaldehyde with aromatic amino phenols. Then, these monomers were converted to their polyphenol derivatives by oxidative polycondensation reactions in an aqueous alkaline medium. Structural characterizations were carried out by FTIR, NMR, and size exclusion chromatography. Cyclic voltammetry was used to determine the electrochemical oxidation-reduction characteristics. Optical properties were investigated by UV–vis and fluorescence analyses. Solid state electrical conductivities were measured on polymer films by four-point probe technique using an electrometer. Thermal data of monomer/polymer and polymers were obtained by TG-DTA and DSC techniques, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and Characterization of PVA/PVP Nanofibers as Promising Materials for Wound Dressing

The PVA/PVP, PVA/PVP with 5% and 10% chitosan and PVA/PVP-Iodine fibers were produced via electrospinning technique. Their morphological and chemical characteristics were examined with SEM, TGA, FT-IR, viscometer and four-point probe conductivity measurement apparatus. The addition of chitosan increased the viscosity and the electrical conductivity of the polymer. The increase chitosan contents resulted in the diameters of the fibers smaller than expected. This was attributed to the increase in the viscosity of the solution and the electrical conductivity of the resulting fibers. The DSC results show that iodine was efficiently cross-linked with the polymer, forming an amorphous structure.     

Influence of pH on recombinant human growth hormone production by Pichia pastoris

BACKGROUND: Effect of pH on recombinant human growth hormone (rhGH) production by Pichia pastoris hGH‐Mut⁺ was investigated at pH = 4.2, 5.0, 5.5, and 6.0. RESULTS: The highest cell concentration was obtained at pH = 6.0 with 53 g L^?1, while the highest rhGH concentration was attained at pH = 5.0 as 0.27 g L^?1. Total protease secretion increased with increase in pH and with the cultivation time. Oxygen uptake rate increased with increasing pH up to pH = 6.0, having the maximum value, 37 mmol m^?3 s^?1, at pH = 5.5. K_La values were similar at all the conditions, having a maximum value of 0.14 s^?1 at pH = 5.0. Taking the final rhGH concentration into account, the most favourable pH was 5.0; where AOX1 expression level showed a similar trend to AOX activity profiles, having the highest value of 9.4 × 10¹⁰ copy mg^?1 CDW at t = 15 h; in parallel to AOX1 expression profile, hGH expression level increased until t = 15 h, with the highest value of 4.0 × 10¹⁰ copy mg^?1 CDW, where a sharp increase in rhGH concentration was obtained. The expression levels of pep4, prb1 and prc1 genes, responsible from the production of proteinase A, proteinase B and, carboxypeptidase Y, were parallel to each other. CONCLUSION: Since it was shown that pH is a crucial operating parameter in fermentation processes using P. pastoris, keeping pH constant at its determined optimum value, pH = 5.0, during the bioprocess is vital in terms of recombinant protein production. Copyright © 2010 Society of Chemical Industry     

The effects of rosemary extract combination with vacuum packing on the quality changes of Atlantic mackerel fish burgers

The effects of the use of antioxidant technology on the quality of mackerel burgers stored at 4 °C were investigated in terms of sensory, biochemical [thiobarbituric acid (TBA), total volatile basic nitrogen (TVB‐N), peroxide value (PV) and free fatty acids (FFA)] and microbiological analyses [total viable count (TVC)]. Fish meat was divided into three groups; the control (C) without rosemary extract, the second group with 0.4% rosemary extracts (Group A) and the third with 0.8% rosemary extracts (Group B). Results showed that the TVB‐N level did not exceed acceptability limit (30–35 mg 100 g^?1) for all groups. TBA value for the control significantly increased from 1.47 to 4.80 MA kg^?1 whereas it slightly increased in treatment groups as the storage time increased. Significantly higher PV and FFA (P < 0.05) were obtained from the control group. Rosemary extract, in combination with vacuum pack was effective in controlling the growth of bacteria and biochemical indices.     

Pomegranate peel phenolics: Microencapsulation,storage stability and potential ingredient for functional food development

In this study, we investigated the effects of microencapsulation conditions on product quality of pomegranate peel phenolics. Our results indicate an optimum air inlet temperature of 160 °C and 1/1 (w/w) or 1/3 (w/w) for phenolics/maltodextrin ratio. No differences were observed amongst the maltodextrins used for coatings. There were also no statistically significant differences in phenolic content of microcapsules for the storage periods of 90 days at 4 °C (p > 0.05). We also evaluated the resultant microencapsulated phenolics for enrichment of the functional properties of regular ice cream used as model food in our studies. Addition of pomegranate peel phenolics at 0.5 and 1.0% (w/w) showed significant improvement of the antioxidant and α-glucosidase inhibitory activities of the enriched ice creams compared with control sample. Antioxidant activity as EC₅₀ and α-glucosidase inhibitory as IC₅₀ of 1.0% phenolic enriched ice creams were 133.3 and 22.9 μg/mL, respectively. More than 75% of the panellists accepted the phenolic enriched ice creams in sensory evaluation, which lends supports to such products for commercial introduction to the general public with the potential as functional foods.